System and method for fracking of shale rock formation

ABSTRACT

The various embodiments of the present invention provide a system for fracking a plurality of shale rocks in a shale reservoir. The system comprises a shock tube for generating a plurality of shock waves a support system for holding the shock tube, a guide tube for directing the shock waves into the shale reservoir, a perforated cylinder for releasing the high pressured shock waves on to the shale rocks and a plurality of packer systems for aligning the guide tube and the perforated cylinder inside the shale reservoir. The shockwaves creates a plurality of fractures on the shale rocks. The shockwaves further cause widening of the existing factures on the shale rocks.

CROSS REFERENCE TO RELATED APPLICATION

The application is a National Phase Application filed with respect tothe PCT Application No. PCT/IN2015/000166 filed on Apr. 9, 2015 with thetitle “A SYSTEM AND METHOD FOR FRACKING OF SHALE ROCK FORMATION”. Theapplication further claims the priority of the Indian Provisional PatentApplication with No. 4633/CHE/2013 filed on Oct. 15, 2013 and post datedby six months to Apr. 15, 2014 the title “A SYSTEM AND METHOD FORFRACKING OF SHALE ROCK USING SHOCK WAVE”. The contents of the abovementioned applications are incorporated in its entirety by referenceherein.

BACKGROUND

Technical Field

The present invention generally relates to a fracking technology andparticularly relates to a field of fracking of Shale reservoir rocks.The present invention more particularly relates to a system and methodfor generating fractures in a shale reservoir by using a plurality ofshock waves.

Description of the Related Art

The availability of petroleum and its products are getting depleted dayby day. The oil source is mainly found in the reservoir rocks which arehighly porous and permeable such as sandstone. Oil shale is anorganic-rich fine-grained sedimentary rock containing kerogen from whichliquid hydrocarbons called shale oil is produced. Extracting oil fromoil shale requires conversion of the solid hydrocarbons in the rock toliquid form, so that they can pumped or processed.

The key to extract these resources is through the process of fracking.Frackng has unlocked massive new supplies of oil and clean-burningnatural gas from dense deposits of shale.

Hydraulic finking is a popular technique used for shale oil extraction.Hydraulic fracking is a process in which large quantity of water isforced into a wellbore and pressurized between two packer systems(confined zone) to open-up the fractures. The injected water flows inthe least resistance path through the fractures and thus opening of thefractures takes place in the weakest zone. Huge amounts of pollutedwater returns to the surface after the process is complete. This wateris polluted with chemicals, salts and even mild radioactivity. Thepolluted water contaminates the groundwater aquifer and also surfacewater resources. Hydraulic fracking is also a highly tedious processwhich requires high skilled workmanship. If the shale gas wells arefound inside the oceans, the requirement of large quantifies of water isnot an issue of concern. But many gas wells are found in the drydeserted areas. In that case the hydraulic fracking technique becomesimpossible to carry out. This technique also involves chemical treatmentprocess and is considered highly uneconomical.

Injection of CO2 is another method having the same objective of inducingfractures. In this method, liquid CO2 is injected into the shaleformation, which has been isolated by inflatable packers. Theintroduction of the liquid CO2 freezes the surrounding fluid inside theexisting fractures. As the liquid CO2 becomes gas, the fluid expandsthereby extending the fractures. Carbon dioxide fracking poses manychallenges besides the lack of infrastructure. Unlike water, gases arecompressible. So it is more difficult for gases to reach the pressureneeded to fracture the rock. Also, the carbon dioxide has to beseparated from the natural gas before shipping the fuel to market, whichadds to costs. And it is probably never economical to install carbondioxide pipelines all the way to every fracking well. More number oftrucks are needed to convey the carbon dioxide when compared with waterfracking. This leads to increase in local noise, pollution, and roaddamage.

Hence there is need for an efficient system and method for fracking, ofoil shale rock which overcomes disadvantages of above fracking methods.

The above mentioned shortcomings, disadvantages and problems areaddressed herein and which will be understood by reading and studyingthe following specification.

OBJECTIVES OF THE EMBODIMENTS

The primary object of the present embodiment is to provide a system andmethod to create fractures M a plurality of shale reservoir rocks andalso to extend the dimensions of existing fractures by using a pluralityof shock waves.

Another object of the present embodiment is to provide a system forgenerating the shockwaves on ground and directing the waves intoborewell.

Yet another object of the present embodiment is to provide a system thatproduce the shockwaves at the point of application inside the borewell,by using combustion of gases.

Yet another object of the present embodiment is to strike the highpressure shockwaves onto the Shale rocks with a high velocity forcreating a plurality of fractures along the weak zone of the shaleformation.

Yet another object of the present embodiment is to widen the existingfractures in the shale rock formation using the shock waves.

These and other objects and advantages of the present embodiment willbecome readily apparent from the following detailed description taken inconjunction with the accompanying drawings.

SUMMARY

The various embodiments of the present invention provide a system forfracking a plurality of shale rocks in a shale reservoir. According toone embodiment of the present invention, the system comprises a shocktube for generating a plurality of shock waves, a support system forholding the shock tube, a guide tube for directing the shock waves intothe shale reservoir, a perforated cylinder for releasing the highpressured shock waves on to the shale rocks and a plurality of packersystems for aligning of the guide tube and the perforated cylinderinside the shale reservoir. The shockwaves creates a plurality offractures on the shale rocks. The shockwaves further cause widening ofthe existing factures on the shale rocks.

According to an embodiment of the present invention, the shock tubecomprises of a driver section and a driven section separated by a metaldiaphragm. The driven section is filled with a low pressure driven gasand the driver section f the shock tube is filled with a high pressuredriver gas supplied by a ugh pressure gas cylinders.

According to an embodiment of the present invention, the guide tube andthe shock tube are connected by an elbow bend. The shock wave travellingthrough the driven section of the shock tube is directed into the guidetube through the elbow bend.

According to an embodiment of the present invention, the diaphragm isruptured using the high pressure gas to produce the shock waves. Theshock waves produced propagate through the driven section.

According to an embodiment of the present invention, the diaphragm isbusted to produce a series of shock waves. Each shock wave possess anincreasing speed of sound, so that they compress into a shockpropagating through the driven gas.

According to an embodiment of the present invention, the perforatedcylinder is placed in a confined zone between the pluralities of packersystems to avoid a leakage of the shockwaves.

According to an embodiment of the present invention, the high pressurejets strike out horizontally into the shale rock formation through theperforations of the cylinder.

The various embodiments of the present invention provide a method forfracking a plurality of shale rocks in a shale reservoir. According toan embodiment of the present invention, the method comprises generatinga plurality of shockwaves in a shockwave tube; guiding the generatedshockwaves into the shale reservoir through a guide tube; ejecting thehigh pressured shockwaves through a perforated cylinder attached to theguide tube; and fracturing the shale rocks by exertion of the highpressure shockwaves onto the shale rocks. The high pressure shockwavescreates a plurality of fractures on the shale rocks. The shockwavesfurther cause widening of the existing factures on the shale rocks.

According to an embodiment of the present invention, the method furthercomprises filling a driven section of the shock tube with a low pressuredriven gas; and supplying a high pressure driver gas to a driver sectionof the shock tube. The driver gas exerts high pressure on a diaphragmfor separating the driver section and the driven section. The diaphragmis ruptured to produce the shockwaves.

These and other aspects of the embodiments herein will be betterappreciated and understood when considered in conjunction with thefollowing description and the accompanying drawings. It should beunderstood, however, that the following descriptions, while indicatingthe preferred embodiments and numerous specific details thereof, aregiven by way of illustration and not of limitation. Many changes andmodifications may be made within the scope of the embodiments hereinwithout departing from the spirit thereof, and the embodiments hereininclude all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

The other objects, features and advantages will occur to those skilledin the art from the following description of the preferred embodimentand the accompanying drawings in which:

FIG. 1 illustrates a side cross sectional view of a fracking system,according to an embodiment of the present invention.

FIG. 2 illustrates a perspective view of a hollow perforated cylinder ina fracking system, according to an embodiment of the present invention.

FIG. 3 illustrates a side sectional view of a shale rock formationindicating an effect of shock waves generated with a fracking system,according to an embodiment of the present invention.

FIG. 4 illustrates a flowchart explaining the steps involved in a methodfor fracking the shale rocks using the shock waves, according to anembodiment of the present invention.

Although the specific features of the present invention are shown insome drawings and not in others. This is done for convenience only aseach feature may be combined with any or all of the other features inaccordance with the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings that form a part hereof, and in which the specificembodiments that may be practiced is shown by way of illustration. Theseembodiments are described in sufficient detail to enable those skilledin the art to practice the embodiments and it is to be understood thatthe logical, mechanical and other changes may be made without departingfrom the scope of the embodiments. The following detailed description istherefore not to be taken in a limiting sense.

The various embodiments of the present invention provide a system forfracking a plurality of shale rocks in a shale reservoir. According toone embodiment of the present invention, the system comprises a shocktube for generating a plurality of shock waves, a support system forholding the shock tube, a guide tube for directing the shock waves intothe shale reservoir, a perforated cylinder for releasing the highpressured shock waves on to the shale rocks and a plurality of packersystems for aligning of the guide tube and the perforated cylinderinside the shale reservoir. The shockwaves creates a plurality offractures on the shale rocks. The shock-waves further cause widening ofthe existing factures on the shale rocks.

According to an embodiment of the present invention, the shock tubecomprises of a driver section and a driven section separated by a metaldiaphragm. The driven section is filled with a low pressure driven gasand the driver section of the shock tube is filled with a high pressuredriver gas supplied by a high pressure gas cylinders.

According to an embodiment of the present invention, the guide tube andthe shock tube are connected by an elbow bend. The shock wave travellingthrough the driven section of the shock tube is directed into the guidetube through the elbow bend.

According to an embodiment of the present invention, the diaphragm isruptured using the high pressure gas to produce the shock waves. Theshock waves produced propagate through the driven section.

According to an embodiment of the present invention, the diaphragm isbusted to produce a series of shock waves. Each shock wave possess anincreasing speed of sound, so that they compress into a shockpropagating through the driven gas.

According to an embodiment of the present invention, the perforatedcylinder is placed in a confined zone between the pluralities of packersystems to avoid a leakage of the shockwaves.

According to an embodiment of the present invention, the high pressurejets strike out horizontally into the shale rock formation through theperforations of the cylinder.

The various embodiments of the present invention provide a method forfracking a plurality of shale rocks in a shale reservoir. According toan embodiment of the present invention, the method comprises generatinga plurality of shockwaves in a shockwave tube; guiding the generatedshockwaves into the shale reservoir through a guide tube; ejecting thehigh pressured shockwaves through a perforated cylinder attached to theguide tube; and fracturing the shale rocks by exertion of the highpressure shockwaves onto the shale rocks. The high pressure shockwavescreates a plurality of fractures on the shale rocks. The shockwavesfurther cause widening of the existing factures on the shale rocks.

According to an embodiment of the present invention, the method furthercomprises filling a driven section of the shock tube with a low pressuredriven gas; and supplying a high pressure driver gas to a driver sectionof the shock tube. The driver gas exerts high pressure on a diaphragmfor separating the driver section and the driven section. The diaphragmis ruptured to produce the shockwaves.

The various embodiments of the present invention provide a system thatproduces a plurality of fractures and widens the existing fractures inshale rock formation using the shock waves. The system produces the highenergy shock waves either on the ground using a shock tube and transmitit to the required location inside a borewell. In an alternate method,the system is configured to produce the shock waves in situ point ofapplication in the borewell by performing combustion of gases suppliedfrom a reservoir above ground.

FIG. 1 illustrates a complete cross sectional view of the frackingsystem, according to an embodiment of the present invention. The shalereservoir layer is present after a plurality of layers of soilformations 101 and rock formations 102. Depending upon the location ofshale reservoir layer 103, a vertical borewell 104 is drilled into theearth. The borewell 104 is extended up to a several hundred to thousandsmeters deep vertically into a shale rock formation 103. With respect toFIG. 1, the fracking system comprises a shock tube 105 for generatingshock waves, a support system 106 for holding the shock tube 105, anelbow bend 107 for directing shock waves generated in shock tube 105into borewell 104, a guide tube 108 for directing the shock waves tobottom of borewell 104, the guide tube 108 is placed in the borewell 104with the help of a casting wall 109, a perforated cylinder 110 forreleasing the high pressured shock waves on to the shale rocks 103 and apacker system 111 for the proper alignment of the system inside theborewell 104. The shock tube 105 is placed horizontally on the groundand is anchored to the support system 106 to avoid jumping of the tube105 due to a reflected pressure created by the propagating shock waves.The shock tube 105 comprises a driver section and a driven sectionseparated by a metal diaphragm. The driven section is filled with a lowpressure gas which is referred as a driven gas. The driver section ofthe shock tube comprises of a high pressure cylinders filled with highpressure, a driver gas. The shock waves are produced by rupturing thediaphragm using the high pressure driver gas. The bursting of diaphragmproduces a series of pressure waves with each shockwave increasing thespeed of preceding shock wave so that the shock waves compress into ashock propagating through the driven gas.

According to an embodiment of the present invention, the shock waveproduced in the shock tube 105 is guided to the bottom of borewell 104using the guide tube 108. The diameter of guide tube 108 is identical tothe shock tube 105 diameter. The guide tube 108 and the shock tube 105are connected by the elbow bend 107 bent at an angle of 90°. The shockwaves travelling through the driven section of the shock tube 105 aredirected into the guide tube 108 through the elbow bend 107. In-order tomaintain a proper alignment of the guide tube 108 inside the borewell104, the packer system 111 is installed at a regular interval. A set ofpacker system 111 is also installed at the bottom of the guide tube 108to ensure a confined zone around the shale gas source formation 103.

FIG. 2 illustrates a hollow perforated cylinder, according to anembodiment of the present invention. The guide tube is attached with ahollow cylinder 110 which has perforation 201 around its walls. A jet ofpressurized shock waves strike out of the perforation 201 in thecylinder 110 into the rock formation, thereby creating the plurality offractures on the shale rock formation. The shock waves further widensthe existing fractures by exerting pressure on the factures. Thediameter of perforated cylinder 110 is equal to the diameter ofborewell. The perforated cylinder 110 is placed in the confined zonebetween the set of packer systems, to ensure that there is no leakage.The high pressure air behind the shock front propagates into theperforated cylinder 110. The high pressure jets strike out the shalerock formation horizontally through the perforations of cylinder 110.

FIG. 3 illustrates a diagram for explaining the effect of shock waves onthe shale rock formation, according to an embodiment of the presentinvention. The shock wave 301 is generated by busting the diaphragm inthe shock tube using high pressure gas. The shock waves 301 aregenerated back to back giving rise to a dynamic series of waves. Withrespect to FIG. 3, the generated shock waves 301 are guided to thebottom of borewell 104 through the guide tube 108. The high pressurejets 301 that emerge out of the perforation of cylinder 110 at theregular intervals, do not affect the walls of the borewell 104 butexerts the pressure on the shale rock formation 103. The pressurecreates the plurality of fractures 302 in the rock formation 103. Incase of the existing fractures 302, the high pressure shockwavespenetrate through the fractures 302 creating a tensile failure, thusextending the length of the joints.

According to an embodiment of the present invention, the shock waves ofrequired strength are produced locally at the point of applicationinside the borewell, by combustion or detonation of combustible gasmixture such as oxygen and hydrogen. The combustible oxygen and hydrogengases are mixed in a required proportion on the ground level and themixture is send into the borewell to burn the gases at a location usingelectrical or solar energy.

According to an embodiment of the present invention, the shock tube istypically manufactured from a plurality of high strength steel tubes forgenerating the shock waves. However, high strength polymer tubes arealso used for deliver the combustible gases to the locations inside theborewell.

According to an embodiment of the present invention, the pressure levelsin the driver section of the shock tube is up to 80 bars. The length ofthe shock tube is varied in multiples of 10 meters. The thickness of thediaphragm installed in the shock tube varies in the range of 1 mm to 5mm. The strength of the shock wave produced is varied according to thethickness of the diaphragm used in the shock tube. The diaphragmmaterial is replaced at a regular interval of time, based on theperformance of the shock tube. According to an embodiment, the shocktube is mounted vertically inside the borewell to send the shock wavedirectly into the wellbore. The diameter of the shock tube is varied inmultiples of 10 millimeter up to 100 millimeters. The depth of the pointfor discharge of shock pressure inside the borehole is varied frommeters to kilometers. The gases used in the shock tube include, but notlimited to, hydrogen, helium, nitrogen and the like. The gases aresupplied from a commercial high pressure cylinder or from a compressoror the gases are manufactured on site.

FIG. 4 is a flowchart illustrating steps involved in a method forfracking the shale rocks using the shock waves, according to anembodiment of the present invention. The method comprising of the steps:the shock wave is generated by busting the diaphragm in shock tube usinghigh pressure gas (401). Shock waves are generated back to back givingrise to a dynamic series of waves. The generated shock waves are guidedto the bottom of bore well through a guide tube (402). These highpressure jets that emerge out of the perforation of cylinder at regularintervals do not affect the walls of the wellbore but exerts pressure onthe shale rocks (403). The pressure creates new fractures in the rockformation (404). When the fractures are already present, the highpressure jets penetrate through the fractures creating a tensilefailure, thus extending the length of the joints (404).

The foregoing description of the specific embodiments will so fullyreveal the general nature of the embodiments herein that others can, byapplying current knowledge, readily modify and/or adapt for variousapplications such specific embodiments without departing from thegeneric concept, and, therefore, such adaptations and modificationsshould and are intended to be comprehended within the meaning and rangeof equivalents of the disclosed embodiments. It is to be understood thatthe phraseology or terminology employed herein is for the purpose ofdescription and not of limitation. Therefore, while the embodimentsherein have been described in terms of preferred embodiments, thoseskilled in the art will recognize that the embodiments herein can bepracticed with modifications.

The present invention envisages a system and method to create fracturesin a plurality of shale reservoir rocks and also to enlarge thedimensions of existing fractures by using a plurality of shock waves.The present invention facilitates utilizing gas instead of water forproducing the fractures in the shale rocks. The use of gas protects theenvironment by avoiding a disposal of tainted/contaminated water in thewater bodies. The present invention aims at reducing the cost ofhandling the fracturing process and the economics involved is expectedto improve significance of the present invention. The present inventionallows a complete free flow of gas from the exposed fracture. When wateris used, mineral and salts react with water forming blockages around thefracture path impeding the path for the gas to reach the well. Since thepresent invention is a dry fracking process, the damage due to ablockage around the fracture path is eliminated, and the cleaning-up ofwell is expedited. The present invention further eliminates arequirement of high skilled workmanship for operating the frackingprocess.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the embodiments herein that others can, byapplying current knowledge, readily modify and/or adapt for variousapplications such specific embodiments without departing from thegeneric concept, and, therefore, such adaptations and modificationsshould and are intended to be comprehended within the meaning and rangeof equivalents of the disclosed embodiments. It is to be understood thatthe phraseology or terminology employed herein is for the purpose ofdescription and not of limitation. Therefore, while the embodimentsherein have been described in terms of preferred embodiments, thoseskilled in the art will recognize that the embodiments herein can bepracticed with modifications.

Although the embodiments herein are described with various specificembodiments, it will be obvious for a person skilled in the art topractice the embodiments herein with modifications.

What is claimed is:
 1. A system for fracking a plurality of shale rocksin a shale reservoir, the system comprises: a shock tube for generatinga plurality of shock waves; a support system for holding the shock tube;a guide tube for directing the shock waves into a shale reservoir: aperforated cylinder for releasing high pressured shock waves on to theshale rocks; and a plurality of packer systems for aligning the guidetube and the perforated cylinder inside the shale reservoir. wherein theshockwaves creates a plurality of fractures on the shale rocks, andwherein the shockwaves further cause a widening of the existing factureson the shale rocks.
 2. The system according to claim 1, wherein theshock tube comprises a driver section and a driven section separated bya metal diaphragm.
 3. The shock tube according to claim 2, wherein thedriven section is filled with a low pressure driven gas, and wherein thedriver section of the shock tube is filled with a high pressure drivergas supplied by a high pressure gas cylinders.
 4. The system accordingto claim 1, wherein the guide tube and the shock tube are connected byan elbow bend, and wherein the shock wave travelling through the drivensection of the shock tube is directed into the guide tube through theelbow bend.
 5. The system according to claim 1, wherein the diaphragm isruptured using the high pressure gas to produce the shock waves, andwherein the shock waves produced are propagated through the drivensection.
 6. The system according to claim 1, wherein the diaphragm isbusted to produce a series of shock waves, and wherein each shock wavepossess a speed and wherein the speed of each shock wave is increased inmultiples of a speed of sound, and wherein each shock wave is compressedto generate a shock that is propagated through the driven gas.
 7. Thesystem according to claim 1, wherein the perforated cylinder is placedin a confined zone between the pluralities f packer systems to avoid aleakage of the shockwaves.
 8. The system according to claim 1, whereinthe high pressure jets strike out the shale rock formation horizontallythrough the perforations of the cylinder.
 9. A method for frocking aplurality of shale rocks in a shale reservoir, and wherein the methodcomprises steps of: generating a plurality of shockwaves in a shockwavetube; guiding the generated shockwaves into a shale reservoir through aguide tube; electing high pressure shockwaves through a perforatedcylinder attached to the guide tube; and fracturing the shale rocks byexerting high pressure shockwaves onto the shale rocks, wherein the highpressure shockwaves creates a plurality of fractures an the shale rocks,and wherein the shockwaves further cause a widening of the existingfactures on the shale rocks.
 10. The method according to claim 9,further comprises steps of filling a driven section of the shock tubewith a low pressure driven gas; and supplying a high pressure driver gasto a driver section of the shock tube; wherein the driver gas exertshigh pressure onto a diaphragm thereby separating the driver section andthe driven section, and wherein the diaphragm is ruptured to produce theshockwaves.